The electrical characteristics of funnel-shaped silicon nanowire (SiNW) solar cells are introduced and numerically analyzed. The funnel-shaped NW consists of a cylinder over a conical unit. Its aim is to maximize the optical absorption over a large wavelength range and hence the electrical efficiency by increasing the number of resonance wavelengths or by enlarging the resonance wavelength range. The conical part has different radii in the axial direction, which increases the number of resonance wavelengths. Further, the coupling between the supported modes by the upper cylinder and the lower tapered cone offers multiple optical resonances required for broadband absorption. The optical characteristics and generation rates through the studied design are obtained using 3-D finite difference time domain. However, the electrical properties are calculated using finite element via the Lumerical device software package. In this regard, radial and axial junctions are examined for the suggested design and compared with the conventional cylindrical SiNW counterpart. In this investigation, short circuit current density, open circuit voltage, fill factor, and power conversion efficiency (PCE) are simulated to quantify the optoelectronic performance of the reported design. Furthermore, the effects of the doping concentration and carrier lifetime on the performance of the funnel-shaped design are reported. The proposed SiNWs offer PCE and short circuit density of 12.7% and 27.6 mA/cm2, respectively, for the axial junction. However, the funnel design with core–shell junction shows an efficiency and short-circuit current (Jsc) of 14.13% and 31.94 mA/cm2, respectively. Therefore, the suggested design has higher efficiency than 6.4% and 9.6% of the conventional cylindrical SiNWs according to the axial and core shell junctions, respectively.
An approach to enhance the ultimate efficiency of the silicon nanowires (Si NWs) solar cell is proposed based on a hybrid population-based algorithm. The suggested technique integrates the ability of exploration in a gravitational search algorithm (GSA) with the exploitation capability of particle swarm optimization (PSO) to synthesize both algorithms’ strengths. The hybrid GSA-PSO algorithm in MATLAB® code is linked to finite-difference time-domain solution technique based on Lumerical-software to simulate and optimize the Si NWs’ geometrical parameters. The suggested GSA-PSO algorithm has advantages in terms of better convergence and final fitness values than that of the PSO algorithm. Further, the Si NWs lattice with optimized diameters and heights shows a high ultimate efficiency of 42.5% with an improvement of 42.8% over the Si NWs lattice with the same diameters and heights. This enhancement is attributed to the different generated optical modes combined with multiple scattering and reduced reflection due to the different heights and different diameters, respectively.
A design of a transverse electric (TE)-pass polarizer based on hybrid plasmonic silicon-on-insulator (SOI) platform is reported and analyzed using full vectorial finite element method. The proposed design has gold nanorods that are injected into the silicon dioxide substrate to tolerate the function of the device, and hence the required polarizing state can be obtained. Detailed design principle is presented, taking advantage of the distinct confinements of the TE and transverse magnetic modes in the core region and their coupling with the surface plasmon modes around the metallic nanorods. According to the positions of the gold nanorods, the suggested plasmonic SOI can be used as a TE-pass polarizer with a compact device length of 1.85 μm with 0.1639 dB insertion losses and extinction ratio of 14.58 dB at wavelength of 1.55 μm. The optimized geometrical parameters offer 3 orders of magnitude smaller than similar devices previously demonstrated on the SOI platform. The proposed design has advantages in terms of simplicity and compactness, which makes it a good candidate to be used in integrated silicon photonics. Further, the compact device size and good performance could provide a simple yet satisfactory solution to the polarization-dependent performance drawback of the silicon photonics devices on the SOI platform.
A design of a highly sensitive multichannel biosensor based on photonic crystal fiber is proposed and analyzed. The suggested design has a silver layer as a plasmonic material coated by a gold layer to protect silver oxidation. The reported sensor is based on detection using the quasi transverse electric (TE) and quasi transverse magnetic (TM) modes, which offers the possibility of multichannel/multianalyte sensing. The numerical results are obtained using a finite element method with perfect matched layer boundary conditions. The sensor geometrical parameters are optimized to achieve high sensitivity for the two polarized modes. High-refractive index sensitivity of about 4750 nm/RIU (refractive index unit) and 4300 nm/RIU with corresponding resolutions of 2.1×10−5 RIU, and 2.33×10−5 RIU can be obtained according to the quasi TM and quasi TE modes of the proposed sensor, respectively. Further, the reported design can be used as a self-calibration biosensor within an unknown analyte refractive index ranging from 1.33 to 1.35 with high linearity and high accuracy. Moreover, the suggested biosensor has advantages in terms of compactness and better integration of microfluidics setup, waveguide, and metallic layers into a single structure.
In this paper, a novel design of hybrid silicon plasmonic transverse electric (TE) pass polarizer based on silicon-oninsulator (SOI) platform is reported and analyzed. The numerical results are obtained by using full vectorial finite element method. The suggested design depends on gold rods that are injected into the substrate in order to tolerate the function of the device and hence the required polarizing state can be obtained. The proposed SOI TE polarizer can achieve -0.19 dB insertion losses with compact device length of 18 μm. Further, the introduced device is easy for fabrication and is compatible with the standard CMOS fabrication process.
In this paper, a novel design of highly sensitive biosensor based on photonic crystal fiber is presented and analyzed using full vectorial finite element method. The suggested design depends on using silver layer as a plasmonic active material coated by a gold layer to protect silver oxidation. The reported sensor is based on the detection using the quasi transverse electric (TE) and quasi transverse magnetic (TM) modes which offers the possibility of multi-channel/multi-analyte sensing. The sensor geometrical parameters are optimized to achieve high sensitivity for the two polarized modes. High refractive index sensitivity of about 4750 nm/RIU (refractive index unit) and 4300 nm/RIU with corresponding resolutions of 2.1×10-5 RIU, and 2.33×10-5 RIU can be obtained for the quasi TM and quasi TE modes, respectively.
Silicon nanowires (SiNWs) are the subject of intense research in solar energy harvesting due to their unique electrical and optical characteristics. The transmission, reflection, and absorption spectra of decagonal Si NWs (D-SiNWs) solar cells have been calculated using a three-dimensional finite-difference time-domain method to present a design guideline for ultra-high efficiency SiNW in solar cell applications. In this study, the structure geometrical parameters of the suggested design are tuned to maximize light absorption. The ultimate efficiency is used to quantify the absorption enhancement of the SiNWs solar cells. A maximum ultimate efficiency of 39.3% is achieved for the reported D-SiNWs, which is greater than that of the previous work of slanting Si NWs by 17.49%.
In this paper, compact three trenched channel plasmonic microring resonator sensor (TTCP-MRRS) on a silicon-oninsulator substrate is proposed and analyzed. The three trenched waveguide is composed of three metal-gaps-silicon structure, where the optical energy is greatly enhanced in the narrow gaps. The full vectorial finite element method is used to numerically analyze the device optical characteristics as a biochemical sensor. As the optical field in the proposed structure has a large overlap with the upper-cladding sensing medium, the sensitivity is very high compared to other dielectric microring resonator sensors. The sensitivity is the ratio between the resonance wavelength shift and the cladding refractive index change, which is a key parameter to describe the sensor performance. The detection limit (DL), which is defined as the minimum refractive index change in the sensing medium that can be detected by the sensor system, is proportional to the resonance line width Δλ or inversely proportional to the resonance Q-factor. So, in order to properly evaluate the sensing performance of the proposed channel plasmonic microring resonator sensor, a figure of merit (FOM) can be defined as the number of resonance line width shift in response to a unit cladding refractive index change. The proposed (TTCP-MRRS) has a compact size and high sensitivity and can be integrated in an array form on a chip for highly-efficient lab-on-chip biochemical sensing applications.
A photonic crystal fiber (PCF) surface plasmon resonance (SPR) based sensor is proposed and analysed. The proposed sensor consists of microuidic slots enclosing a dodecagonal layer of air holes cladding and a central air hole. The sensor can perform analyte detection using both HEx 11 and HEy 11 modes with a relatively high sensitivities up to 4000 nm=RIU and 3000 nm=RIU and resolutions of 2.5×10-5 RIU-1 and 3.33×10-5 RIU-1 with HEx11 and HEy11, respectively, with regards to spectral interrogation which to our knowledge are higher than those reported in the literature. Moreover, the structure of the suggested sensor is simple with no fabrication complexities which makes it easy to fabricate with standard PCF fabrication technologies.
In this paper, a novel design of tellurite photonic crystal fiber (PCF) is presented and analyzed. The proposed design is analyzed using full-vectorial finite-difference method (FVFDM). The analyzed parameters are the birefringence, effective mode area, nonlinearity and dispersion for the two fundamental polarized modes. The effects of the structure geometrical parameters on the modal properties are studied in detail. The numerical analysis reveals that the proposed design has high birefringence of 0.10568 and high nonlinearity of 4784 W-1 Km-1 and 4030 W-1 Km-1 for the quasi transverse magnetic (TM) and quasi transverse electric (TE) modes, respectively at the operating wavelength of 1.55 μm with low losses for the two fundamental polarized modes. Also, the dispersion of the reported design can be tailored to achieve flat and zero dispersion at the desired wavelength.